917~920 异步提交表单，Servlet，Dao，Servlic代码实现

异步提交表单

　　在此使用异步提交表单是为了获取服务器响应的数据。

　　　　因为我们前台使用的是html作为视图层，不能够直接从servlet相关的域对象获取值，只能通过ajax获取响应数据

RegistUserServlet

package cn.itcast.travel.web.servlet;

import cn.itcast.travel.domain.ResultInfo;
import cn.itcast.travel.domain.User;
import cn.itcast.travel.service.UserService;
import cn.itcast.travel.service.impl.UserServiceImpl;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.commons.beanutils.BeanUtils;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.Map;

@WebServlet("/registUserServlet")
public class RegistUserServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //验证校验
        String check = request.getParameter("check");
        //从sesion中获取验证码
        HttpSession session = request.getSession();
        String checkcode_server = (String) session.getAttribute("CHECKCODE_SERVER");
        session.removeAttribute("CHECKCODE_SERVER");//为了保证验证码只能使用一次
        //比较
        if(checkcode_server == null || !checkcode_server.equalsIgnoreCase(check)){
            //验证码错误
            ResultInfo info = new ResultInfo();
            //注册失败
            info.setFlag(false);
            info.setErrorMsg("验证码错误");
            //将info对象序列化为json
            ObjectMapper mapper = new ObjectMapper();
            String json = mapper.writeValueAsString(info);
            response.setContentType("application/json;charset=utf-8");
            response.getWriter().write(json);
            return;
        }

        //1.获取数据
        Map<String, String[]> map = request.getParameterMap();

        //2.封装对象
        User user = new User();
        try {
            BeanUtils.populate(user,map);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }

        //3.调用service完成注册
        UserService service = new UserServiceImpl();
        boolean flag = service.regist(user);
        ResultInfo info = new ResultInfo();
        //4.响应结果
        if(flag){
            //注册成功
            info.setFlag(true);
        }else{
            //注册失败
            info.setFlag(false);
            info.setErrorMsg("注册失败!");
        }

        //将info对象序列化为json
        ObjectMapper mapper = new ObjectMapper();
        String json = mapper.writeValueAsString(info);

        //将json数据写回客户端
        //设置content-type
        response.setContentType("application/json;charset=utf-8");
        response.getWriter().write(json);


    }
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    this.doPost(request,response);
    }


}

UserService，UserServiceImpl

public interface UserService {
    //注册用户
    boolean regist(User user);

}

public class UserServiceImpl implements UserService {
    private UserDao userDao = new UserDaoImpl();

    //注册用户
    @Override
    public boolean regist(User user) {
        //1.根据用户名查询用户对象
        User u = userDao.findByUsername(user.getUsername());
        //判断u是否为null
        if(u !=null){
            //用户名存在，注册失败
            return false;
        }
        //2.保存用户信息
        userDao.save(user);
        return false;
    }
}

UserDao，UserDaoImpl

public interface UserDao {
    //根据用户名查询用户信息
    public User findByUsername(String username);
    //用户保存
    public void save(User user);
}

public class UserDaoImpl implements UserDao {

    private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());
    //根据用户名查询用户信息
    @Override
    public User findByUsername(String username) {
        User user = null;
        try {
            //1.定义sql
            String sql = "select * from tab_user where username = ?";
            //2.执行sql
            template.queryForObject(sql,new BeanPropertyRowMapper<User>(User.class),username);
        } catch (Exception e) {
        }
        return user;
    }
    //保存用户信息
    @Override
    public void save(User user) {
//1.定义sql
        String sql = "insert into tab_user(username,password,name,birthday,sex,telephone,email,status,code) values(?,?,?,?,?,?,?,?,?)";
        //2.执行sql

        template.update(sql,user.getUsername(),
                user.getPassword(),
                user.getName(),
                user.getBirthday(),
                user.getSex(),
                user.getTelephone(),
                user.getEmail(),
                user.getStatus(),
                user.getCode()
        );
    }
}

public class UserServiceImpl implements UserService {
    private UserDao userDao = new UserDaoImpl();

//注册用户
@Override
public boolean regist(User user) {
        //1.根据用户名查询用户对象
User u = userDao.findByUsername(user.getUsername());
//判断u是否为null
if(u !=null){
            //用户名存在，注册失败
return false;
}
        //2.保存用户信息
userDao.save(user);
        return false;
}
}